Automatic control of the circuits of electric heating apparatus, etc.



M..H. SHOENBERG.

AUTOMATIC CONTROL CTF-THE CIRCUITS 0F ELECTR-IC HEATING APPARATUS, ETC.

` APPLICATION FILED JULY 8,1919.

1,405,450. i Patented Fen-'7, 1922iv 2 SHEETS-SHEET L.

A 72??""4" gmc/nm a4 my,

M. H. SHOENBERG. AUTOMATIC CONTROL 0F THE CIRCUITS 0F ELECTRIC HEATING APPARATUS, ETC. APPLICATION min JuLY 8, 1919.

1,405,450, Patented Feb. 7, 1922.

2 SHEETS-SHEET' 2.

UNi'ri-:o STATES PATENT foi-Fica m'roN n. suoniamo, or sur Francisco, cALuomru, assreiroa To maarre morne Dnvm'erxm'r coirrm, A conrona'rioN or cnn-cama.

.Auronric ooit'raor. orma ciacurrs or anacraic `:martire arrm'rus, are..

To all whom it may o'omem: p

Beit known that I, MILTON H. SHoEiaBEiic, acitizen of the United States, residing at San Francisco, in the county of San Fran-VA cisco and State of California, have invented certain new and useful Improvements in Automatic Control o the Circuits of Elec tric Heating Apparatus, etc., of'which the following -is` a specification. Y

This invention relates to the control of electric circuits, and while especially adapted for controlling the circuits of electrieheaters, such as water heaters, percolators, sterilizers, electric irons, etc., it may also be used as a thermally controlled overload switch `for electric circuits generally. i

. The main 'purpose of my invention ,is to provide a switch Iwhich can be manually o'perated toclose and open an electric circuit and which will'operate automatically to o en the circuitin case of anuoverload'or an un ue flow of current, such control being effected by a thermally actuated switch member.v .A

- further vobject of my invention is'xto provide an auxiliary. controlling Adevice cooperating with the thermal switch member to. open the circuit, such auxiliary member being sepaiate from the switch and directlyaifected by the condition of the work being effected.

. ".In the accompanying drawings, Figures 1, 2,3 and 4, are elevations partly in lsection of a switch embod my invention and showing the switch in different positions; Fig. 5, 1

is aivertical sectional view of an electricwater heater showing one form of auxiliary circuit controlling device, actuated by water P pressure, which acts in conjunction with the thermal element lin the switch to eect a coinplete automatic control of the heating circuit; Figs. 6, I and 8 are detail views-of the .parts of the pressure actuated device; Fig. 9.

is a 'dia atic illustration of the vcircuit containing a'waterheater and embodying my automatic controlling features; Fig. 10 show sfmy automatic controllin .-.switc'h applied to the heating circuit o an electric iron; Fig,'11 showsainodification of tlie latter; and Fig. l12, is a sectionals view of a modified form of my automatic switch,

vMy combined inanual and thermally controlled switch ma be enclosed in aY suitable casing 1 and may inserted as a small pendant switch in the usual cord.conductors connected to heating devices, such -as water heaters connected to faucets, electric irons,

- spring 23, presses the bowed a end of the blocg,

sanitation i Letten raient; faten'ted Feb, 7, .1922 application inea Juiy si; 191s, semi in. 309,433.

percolators, etc. i The switch mechanism is 'carried by a suitable insulating block 3, sc-

cured within the casing. The movable 'con-v tact element comprises a pair of spring arms .4, 5 secured at one end to the insulating bloclr. by a plate the free ends normally bearing against theV angle plate 8, which -constitutes a fixed contact post and is connected to the conductor 10. f-

A latch member comprising a spring strip having one end 15l secured to the block 3 by a screw -17 constituting a binding post tol it pressed inward by the thumb button 20. y

It will be observed that when the s ring contact strips 4, 5 are ypressed inwar` ly by the thumb button20, the inner strip 5 will snap under the latch hook '15 and be retained while the outer shorter strip -4 will spring back against the angle post 8, as indicated in Fig. 3. T o release the contact strip 5, the thumb button 21 is pressed inwardly until the-leaf rtion 15" of the latch member toward the b ock 3, thereby iia-ttening it and causing the hook end 15 to move outwardly and thus releasing the end ofthe contact strip 5, which syrings back into the initial position shown in ig. 2.

The arts thus far described constitute a manually controlled snapswitch -for closing and opening an electric circuit. For ther ur of automatically moving the hook 15 of the latch 'member outwardly to release the contact strip 5 upon an undue flow of current or an undue heating of the translating. device, I provide a spring arm 25,

secured at its inner end to the plate 27 which is fastened to the block 3, andliaving its vouter endbent outwardly f and bearing against the inner side of the latch member.

The spring arm 25 is normally restrainedl from ushmg outwardly 'the latch by a t ermostatic-wire 30, which is secured at one end to late 31, fastened to the upper and atthe other end i f '-4 throu han' aperture in the arm 25,

rovi ed with im enlarged end :io w

ars against the llower side of thelatch.

T liethermal wire 30 is connected to the controlling circuitywhich is sometimes a shunt circuit, by a conductor 34 attached to the screw 32 onstitutin a binding post. The j.

through angle piost 8, spring arm 4, springv arm 5, latch lio 15, spring arm 25, thermal wire 30 and terminal vconductor 34. If there is an undue flow of current the thermal wire 30 is abnormally heatedand expands thereby permitting the spring arm 25 to move' outl wardly and push the latch until the hook 15 moves outwardly sufficiently to release the spring contact ar1n5, thereby breaking the circuit. It will be observed that the switch is at all times also under manual con# trol since the latch may be released instantly by pressureupon the push button 21.

In order that the modified form' of switch shown in Fig. 12 may be understood from the foregoixig 'description of the switch arts v and their function, I vhave designated) the corresponding parts-by the same-reference characters. In this orm both the circuit closingbutton 20 and the opening button 21 are placed on the same side and to better accommodate this arrangement the angle post 8 is placed in an intermedia e position on the block 3.

In. case it is desirable to vary` the tension i y on4 the thermal wire 30, the fixed end may 36 be attached to a threaded nipple 30b ytore,

ceive the adjusting nut 33, as shown' in Fig. 3.

i My invention comprises also a controlling circuit which includes :an auxiliary controlling element cooperating with the thermal 40 element of the switch to elect the breaking of thecircuit through the electric heater or other translatingdevicer. In Fig. 5, I have shown the auxiliary controllin elementY in the'lform of a pressure actuate diaphragm which operates to close a' circuit in shunt A to the thermal switch element. The water heater illustrated comprises a casing 40, having a cylindrical heating chamber or channelI .244 through which the water flows and is heat- 5-0 ed by the heating element 41. 1 The closure for the upper end of the heating chamber comprises separable .insulating plugs 43, 45 which are fastened together by screws 4B, and clamp between them a rubber disk 47,

the plugs being centrally recessed to provide a space permitting lateral movement of the central portion of the disk. After the closure is vinserted in the casing the screws are,tightened and cause the periphery f the' disk to 's read or bulge 'otjwardly as indicated in Fig. 7, thereby forming a watertight joint withuthe inner wall of the casing, theh disk thus constituting a gasket as well as a diaphragm. "The diaphragm portion and gasketportion may bemadeseparate as shown in Fig. 7,rat 47, 47h. The lower side of the diaphragm is in communication with the water chamber through a small channel 48. Contacts 50, 51 carried by the plug 45 are vnormally separated and are pressed together` by the plunger 53 when the diaphragm is forced upwardly by the water pressure in the chamber 44. The terminals 41a, 41'J of the heatin element pass through. the plugs and are so dered or otherwise secured yto binding posts 56, 57. The lower `pring contact strip 50 is Aconnected to the binding post 57. In Fig. 9, I have shown diagrammatically the manner in which the Water heater is connected in circuit, with the switch, the`corresponding parts being designatedvby the same reference characters. The operation will be clear from the previous description ofthe separate parts. Assuming that the g5 push button 20 has been operated' to engage the contact`arm 5 under the latch hook 15,

'the current Hows from the conductor '10,

to angle post 8,v arm 4, arm 5, hook 15G, latch member 15", binding post' 17 to conductor 12. If the water has been turned on in the water heater, by ope'ning the faucet, the pressureV forces the diaphragm 47 upwardly and closes the contacts 50, 51 of the auxiliary control device. The current will therefore'owpthrough contacts 51 and 50, through the heating element 41 and out to the main negative conductor. It will be observed that there is als' a circuit from the hook\15 of the latch member through the thermal wire 30 and conductor leading lfrom the terminal 34 directly to the heating unit 41, but it will be understood that as the resistance of the thermal wire is greater than the other path which shunts it through the contacts 50, 51, very little current will traverse the thermal wire.' v If, however, the water is shut olf so that there is no` water pressure in the heater chamber, and the diaphragm is therefore retracted leaving the contacts 50, 51 open, 'all of the current must` traverse the path -through the thermal wire '30, causing it to become abnormally heated, whereupon it instantlyexpands and permits the latch to releasethe contact arm 5,*thereby opening the circuit.

`It is apparent, therefore, that the heating coil 41 can never .be in danger of burning out because the action of v the thermal wire will-always trip the ,latch to open the circuit whenever there is no water i'essure in the water heater to act upon the iaphiyagm. lIf it is desired, however, to change from hot to 4cold water while'tlie water is turned on and constantly iiowing through the channel in the water heater, the electric current may be cut o or turned on manually at will by manipulating the push buttons 20 and 21.

The auxiliary control device which cooperates .with the thermal switch element 130 ido "itl

tion of heat in the electric vheater or otherl translating device. I have shown such van auxiliary Idevice in .connection 'with an electrically heated latviron in Fig. 10. As before stated, I have designated the cor-v responding parts #by the reference characters previously used.

` While a flat iron is being moved over the dampened clothes in the process of Ironing,

and rapidly abheat is being constantly stracted from the iron and this energy is supplied by the electric heating coil or unit within the iron. If, however,`the iron is allowed lto remain in one place inadvertently or through ignorance or carelessness while the current is on, the heat accumulates and frequently' scorches the clothing or ironing board 'cover and sometimes causes them to ignite. My invention provides aneiiicient safeguard against such accidents by', automatically cutting od the current as soon as the heat inthe iron becomes abnormal.

In Fig. 10 the iron is indicated by the outline and the heating unit or coil by 41. Within theI enclosed chamberof the iron I place a short length of wire 62, of iron or other suitable material having a high temperature coeiiicient.' This is connected in such a manner that normally the current iows through 'this length of iron wire in series with the heating coil and in shunt to the thermal element of the switch. As long as the heat vis being abstracted from the ironlwhile in use, the auxiliary element 62 will not become abnormally hot. When the iron is allowed to remain in one spot, the heat accumulates until the iron element 62 reachessuch a temperature that its increased resistance causes a sufhcient amount automatically trip ythe latch and open the` of current to take the ,other shunt path through the thermal switch element 30, to

main circuit. e

Normally the current flows from the positivepmain conductor by way of the angle post 8, contact strip 4, contact strip 5, hook 15, latchmember 15", terminal conductor 12,- auxiliary.. iron wire element 62, to the branching point 66, then through the heating .unit 41 of the-iron and out to the negative mainy conductor.

hook 15c through the thermal element 30,

' l and terminal conductor 34 to the branching I 'and accumulates, the .increase in heat aug- 65 ments the resistance of the iron wire eleheating It will be observedv that there is also a shunt path from the/latch ment 62 andc'iusescurrent to 'traverse the shuntpath through the thermal element 30,

,resulting in the movement of the latch to open the circuit.

When it is not convenient to place the auxiliary controlling element 62 within the chamber of the flat iron, it may be embodied in the stand upon which 'the iron rests when not in use, as illustrated in Fig. 11. The

element 62 may be placed between 'sheets of mica 68 or other suitable insulating maf.

terial, and secured to Vthe top of the stand or iron-rest y69.. The electrical connections are the same as invF ig. 10. In this case the thermal element opens the switch only if the iron is allowed to remain idl`e by resting on the stand for any appreciable or prede` termined period of time. A

It will be evident to electrical engineers and others skilled in this art, that my invention iscapable of many adaptations and uses which will readily suggest themselves. rlhus when used in connection with electrically heated sterilizers or percolators, the auxiliary controlling element 62 may be immersed in the watersc that in case the water boils away until the wire is exposed, the

resistance of said auxiliary element will ima thermo-element Icontrolling saidlatchl member, an auxiliary circuit in shunt to said thermo-element, and means actuated by 'an abnormal condition Aof the heating apparatus operating to cause an abnormal current to now-through the thermo element to Ithereby release vthe latch member and open the switch contacts. p l

2. In a system of control for electric heating apparatus, a switch in circuit with the electrlc heater, comprising manual' means for closing and for opening the switch contacts, a thermally controlled latchmember for'holding the contacts in closed position, a thermo-element controlling said latch -memben an auxiliary circuit in shunt to said thermo element, and means in said shunt circuit actuated by the increased heat condition of the heating apparatus operating to cause an'v abnormal current to How through the thermo element to cause the latch member to automatically open the` switch contacts.

. 3. In a system of control for electric apparatus, a switch in circuit with iso,

i l i i 1 f the electric heater, comprlsmg manual means for closing and Afor opening the switch contacts, a thermally controlled latch mem-` l ber for holding thecontacts in closed position, a thermo-element controlling said latch member, and means for shunting a one of saidvblades, means for moving the-l blades across said latch whereby one will be f retained thereby, manually actuated means for releasing the latch, and an auto-v matic 'latch releasing device embodying a thermal wire normallyholding said latch in restrained position, said device operating to automatically push the latch outward upon the flow of a lcritical current through the thermal wire. v

5. A switch for controlling the circuit of an electric translating apparatus, comprising apair of springcontact blades. ofdifferent lengths, a terminalcontactforming a back stop for said blades, a movable latch normally in the path of the longer blade, a

push button for moving the blades acrossv said latch whereby the longer one will be retained thereby, and van .automatic latcli releasing device embodying a thermal wire operating to release said blade from the latch upon the iow of a predetermined current therethrough.

6. In a switch as'deined in claim 5, manu- -ally actuated means for lmoving the latch to release the retained blade at will. l

In testimony whereof I Aailixmy signature.

.,MILTON H. sHoE'NBERe 

